Marine biofouling refers to the undesirable colonization of microorganisms, algae, and animals on artificial surfaces immersed in seawater and also causes bio-corrosion for commercially important marine structures. The settlement and accumulation of biofoulers such as barnacles, bryozoans, and mussels on submerged substrates are a worldwide problem in marine systems and create massive technical and economic challenges for maritime industries, marine aquaculture, and cooling systems of power plants (Callow and Callow, 2002; Qian et al. 2007; Sievers et al. 2013)). For instance, large numbers of fouling organisms on ship hulls result in potential speed reduction and loss of maneuverability, thereby severely increasing fuel consumption of navigation (Yebra et al., 2004). The estimated annual cost of biofouling organisms is over $6.5 billion (Bhadury and Wright, 2004). In addition to huge material and economic losses in marine operations, fouling organisms on ship hulls also generate a series of environmental problems such as the invasion of non-native species (Davidson et al. 2009).
In the past, marine antifouling paints, mainly based on toxic heavy metal biocides (eg copper, lead, arsenic, cadmium), were widely used to control biofoulers. Organotins such as tributyitin (TBT) have been the most effective antifouling agents for several decades. However, an uneasy concealed danger behind the efficiency of these booster biocides is the acute toxicity to some non-target marine organisms even in the ng 1−1 range (Alzieu, 2000). The application of coatings containing organotins to ships has been totally banned by the International Maritime Organization (IMO) and Marine Environmental Protection Committee (MEPC) since 2008 (low Callow and Callow, 2011; Li et al., 2013)). Unfortunately, the alternatives to TBT that are currently used in market either contain copper, or Irgarol 1051, diuron, zinc pyrithione, chlorothalonil, and Sea-Nine 211 and can also have deleterious effect effects on ocean environment (Bellas, 2006; Thomas and Brooks, 2010). Therefore, the exploitation of effective and environmentally benign antifouling compounds is becoming an urgent requirement for marine coating industries.
To identify nontoxic and effective antifouling substances, active natural products have been extracted from marine sessile organisms such as corals, sea squirts and sponges (see reviews by Faulkner (2000) and Fusetani (2004)). However, in most instances, the yields of the active compounds by these marine organisms were too low to be developed into antifouling agents. To overcome this problem, much attention has been paid to the large-scale fermentation of microorganisms in recent years (see reviews by Fusetani (2011) and Qian et al. (2010, 2015).